Method and apparatus for feeding balls to grinders and lappers



F. F. DIETERICHS METHOD AND APPAR BALLS TO GRIND 8 Wm wn W m-J AN .0 m I k wmwhmllg mn ww V w, n M 4 fi NQ Q my Oct. 2, 1956 Unite gtates Patent L'IETHOD AND APPARATUS FOR FEEDING BALLS T GRINDERS AND LAPPERS Frank F. Dieterichs, New Britain, Pa., assignor to Joseph G. Carpenter, Philadelphia, Pa.

Application December 17, 1953, Serial No. 398,838 6 Claims. (Cl. 51-130) This invention relates to feed mechanisms for grinders and lappers and more particularly to a recirculating mechanism for feeding minute metal balls to a grinding or lapping machine of the type requiring successive processingefiiciently and economically.

In order to obtain a high degree of uniformity in the manufacture of metal balls, it is of the utmost importance that all of the balls be passed through a grinding or lapping machine an equal number of times.

In prior art devices I have found that when very small balls are processed they have a tendency to become lodged in the cracks and crevices of the magazines unless the component parts of these magazines are machined to close tolerances. This, of course, involves considerable first cost. Furthermore, grinding and lapping liquids have a tendency to be carried as a coating on the balls into the recirculating mechanism where the liquids exert capillary attraction on individual balls and cause them to adhere to the elements and prevent the recirculation thereof. Even in the absence of such liquids in the feed mechanisrn, static electricity retains individual balls in the recirculating device so that a relatively high percentage of balls are not properly recirculated and inaccurately processed balls result.

A principal object of the invention is to provide a feed mechanism wherein a very high degree of quality control is attained by the use of the capillary attraction of the grinding and lapping liquids which thereby prevents the accumulation of undesirable static electricity normally occasioned in mechanical feed devices.

A further object of the invention is to provide a feed device of the stated type wherein the principal object is attained with a minimum of collisions among the balls.

A still further object of the invention is to devise a method whereby large quantities of metal balls of a high degree of uniformity may be manufactured.

These and other objects of the invention and the various features and details of the construction and operation thereof are more fully set forth hereinafter with reference to the accompanying drawings in which:

Fig. 1 is a vertical elevational view, partly in section, of a circulating feed device made in accordance with the present invention;

Fig. 2 is a view taken substantially on line 22 of Fig. 1;

Fig. 3 is a view taken substantially on line 33 of Fig. l; and

Fig. 4 is an enlarged fragmentary view in section of the venturi pump employed in the device of Fig. 1.

With reference to the drawing and more particularly to Fig. 1, it will be seen that numeral designates a conventional ball grinding or lapping machine of the type wherein the articles to be abraded are arranged to travel in a preselected path in engagement with the grinding wheel or lapping plate. During the finishing operation in the grinding or lapping machine, the balls are in a bath of cutting oil or like liquid. In this instance, the abraded articles and the working liquid are discharged from the grinding machine by means of the chute 11 to the funnel 12 where the balls settle to the bottom. This funnel is provided with an outwardly extending peripheral flange 13 apertured at 14 to provide for the overflow of the working liquid that accompanies the balls. The overflow liquid flows into the annular chamber 15 from which it flows by means of a pipe 16 to the sump 17, where minute particles from the grinding operation are settled out.

In accordance with the invention, uniformevacuation of the funnel 12 is afforded by means of the jet pump 18, actuated by means of oil drawn from the sump 17 by the pump 19 through the pipe 22. The balls are then carried by the fluid stream of the jet pump to a hopper 49 where they are stored until they are again passed through the finishing machine as described more fully hereinafter.

As shown in Fig. 4, the jet pump 18 comprises an end fitting 23 threaded at 24 and an oppositely disposed fitting 25 maintained in spaced relation by the spacer 26 provided with internal threads 27 for engagement with the thread 24, and internal threads 28 for engagement with the threads 29 of the fitting 25. The fitting 25 is threadably apertured at 32 for the reception of the jet nozzle 33, An orifice element 3.4 is provided with a sleeve portion 35 threadably received in the fitting 25. This orifice portion is provided with an internal chamber 36 having a cylindrical portion 37, a frusto-conical portion 38, and an elongated frust -conicle portion 39, the entire cavity being formed as to produce, in conjunction with the flow of oil through the nozzle 33, a venturi action through the orifice 42 of the funnel 12, and the fitting 40,

threadably received in the sleeve 35. justment of the nozzle with respect to is afforded by the knurled wheel 43. slotted at 44 to provide access to this Wheel. Leakage of oil from the fitting 23 is prevented by the seal 45, retained in position by the packing gland 46.

In the operation of the jet pump, oil spurting from the restricted orifice causes a low pressure area in the chamber 37 which causes the ball and the concomitant oil to be drawn in an orderly manner from the funnel 12 and to be forced successively through the chambers 38 and 39 and into the pipe 48 which is preferably of flexible abrasion resistant plastic such as polyethylene or the like. The pipe 48 carries the balls in the stream of oil into the hopper 49.

The hopper is surrounded by an open-topped annular chamber 52 to receive the oil overflowing from the hop- The bottom of the chamber 52 is provided with a discharge outlet sloped as indicated at 53 to permit passage of the overflow oil through the pipe 54 back to the sump 17.

Periodic discharge of the balls from the hopper is afforded by the agitator 55 which is intermittently raised Longitudinal adthe chamber 36 The spacer 26 is 47 of the nozzle 33 and allowed to fall by a cam 56. The cam is rotated by means of a motor 57 through a reducing gear train 58. A cam follower 59 mounted on the arm 62 causes rotation of the shaft 63 so that the sheave 64 is rotated through an are. A chain 65 is secured as indicated at 66 to the peripheral groove 67 of the sheave 64 so that as the shaft 63 oscillates, the chain by means of an agitator shaft 68 moves the agitator upwardly and allows it to settle with the surrounding balls in the hopper. The agitator is timed to raise only when the feeder member has discharged a substantial portion of its load, allowing the balls to rush into the feeder and cause a substantial movement or the whole mass of balls in the hopper. Because of the action of the agitator, the feeder member 72 is kept supplied with balls and a controlled flow of balls from its mouth is maintained. It should be noted that the hopper 49 is filled with a supply of liquid which flows from the bottom of the hopper with the balls as the the pressure of the,

agitator 55 is displaced in the hopper. Since the liquid flows with the balls, there is little tendency for the balls to adhere to the elements of the mechanism by reason of the capillary action of the liquid. In fact, the liquid flow assists the movement of the balls through the hopper. The agitator 55 is preferably of double conical configuration, so that the balls tend to fall into concentric annular layers at the bottom of the hopper. Initially, the balls of only the outermost of these layers are permitted to escape when the agitator is raised. When the agitator is fully raised, the liquid flowing between the agitator and the hopper carries the lowermost layers of balls into the feeder member 72. When the agitator drops, it settles on top of the balls in the feeder member and the lower conical surface of the agitator cooperates with the frus-toconical shape of the bottom of the hopper to cause the remaining balls in the hopper to roll downwardly to form another annular layer. The particular shape of the hopper and the agitator insures that all of the balls in the hopper are passed into the feeder member 72 in substantially the same sequence they were fed from the pipe 48, thereby insuring that the balls are all processed an equal number of times; in other words, one ball does not pass through the feeding apparatus at any substantial greater rate than the remaining balls.

The feeder member 72 receives the balls from the hopper in a bath of liquid and directs them to the feed chute of the finishing machine 10. To insure proper distribution of the balls over the width of the chute 74, the feeder member 72 is formed with a plurality of outwardly-fanned grooves 73 (see Fig. 3) which cooperate to control the discharge of the balls from the feeder, as set forth above. The balls are carried down the chute in a bath of liquid and are introduced into the finishing machine. The liquid preferably is the same liquid used in the finishing process so as to insure that the balls are properly finished in the machine 10. Thus, since the balls are continuously surrounded by liquid, the adverse efliect of the capillary action is eliminated.

It will be apparent from the above that the recirculating feed mechanism herein-described is capable of feeding a comparatively large number of small metal balls suc cessively and uniformly to a grinding and lapping machine. I have found that balls ranging in diameter from 0.015 inch to inch may successfully be recirculated in this device. Because of the transportation of the balls in a liquid stream, the adverse effect of fluid surface tension on individual balls is eliminated so that the present invention may be utilized in feeding balls of a diameter as small as ,6 inch. This cannot be done by mechanical means. To accommodate balls of different diameters, the nozzle 33, fitting 40 and orifice element 34 may be replaced by corresponding elements. of varying dimensions as desired. In the operation, I have found that lifting of the conical agitator approximately one inch every thirty seconds to two minutes, depending upon the size of the balls being processed, provides a sufficient uniform feed. The above described apparatus is constructed and arranged to circulate balls approximately fifty to one hundred times in the grinding operation and up to one thousand times for the combined grinding and lapping operation so a high degree of accuracy may be attained.

I claim:

1. A method for recirculating metal balls from and to a surface-finishing machine for said balls comprising the steps of collecting the balls discharged from said machine in an open bottomed funnel with the working liquid from said machine, forming a liquid stream adjacent said bottom opening to create a low pressure area adjacent thereto and thereby entrap the balls and liquid from said funnel, flowing said balls and said liquid to a storage hopper (allowing said balls to settle to the bottom of said hopper, discharging said balls and said liquid from the bottom of said hopper, and flowing said balls and said liquid back into said surface-finishing machine.

2. In combination with a surface finishing machine for balls having inlet means and discharge means respectively receiving and discharging bails and working liquid having a specific gravity less than the specific gravity of said. balls, a recirculating feed mechanism comprising a dis-' charge chute positioned adjacent the discharge means of said machine to receive the balls and working liquid discharged therefrom, a funnel underlying said discharge chute to receive the balls and liquid from said discharge chute, said funnel being open at its bottom, a supply of the working liquid, nozzle means adjacent said bottom opening operatively connected to said liquid supply and operable to create a liquid stream having reduced pressure to thereby draw said balls and liquid from said funnel opening and convey the same in said liquid stream, a conduit connected to said nozzle to carry said liquid stream, a hopper disposed in fluid communication with said conduit to receive and collect the balls and liquid from said conduit, a bottom aperture in said hopper, and means connected to said aperture to direct the balls and liquid from said aperture to the inlet means of said surface finishing machine.

3. Apparatus according to claim 2 including an agitator mounted in said aperture of the hopper, and operating means for said agitator operable intermittently to permit escape of a quantity of balls and liquid collected in said hopper from said aperture and into said directing means.

a 4. Apparatus according to claim 3 wherein the bottom portion of said hopper is frusto-conical, and wherein further said agitator is of double conical conformation to engage in said aperture, the upper surface of said agitator cooperating with said hopper bottom portion to dispose said balls in concentric rings therein whereby upon operation of said agitator, it discharges the lower and outer-most concentric rings of balls from said bottom aperture of said hopper.

5. Apparatus according to claim 2 including an annular chamber surrounding said funnel at the upper end thereof to receive working liquid overflowing therefrom, and conduit means from said annular chamber to said supply whereby said supply is replenished with liquid overflowing from said funnel.

6. Apparatus according to claim 2 wherein said directing means comprises a return chute in communication with said surface finishing machine inlet and a feeder member between said hopper bottom aperture and said return chute, said feeder member having a plurality of outwardly fanned grooves operable upon discharge of balls from said aperture to distribute the balls evenly over the width of said return chute whereby uniform feed back of the balls is accomplished.

References Cited in the file of this patent UNITED STATES PATENTS 727,030 Tilghman May 5, 1903 1,061,241 Hirth May 6, 1913 1,252,365 Schaum Jan. 1, 1918 1,772,365 Pratt Aug. 5, 1930 1,908,220 Chapman May 9, 1933 1,914,991 Ooghlan June 20, 1933 2,299,307 Cornell Oct. 20, 1942 2,372,957 Keefer Apr. 3, 1945 2,453,458 Reed Nov. 9, 1948 FOREIGN PATENTS 294,871 Germany Oct. 2, 1916 

